I just thought I'd post an old trick for recovering copper washers (such as around fuel lines or injector pipes) after dismantling unions. (As I didn't practise what it preach and had a leak recently.....)
The copper will have most likely work-hardened, so hang it on some wire - or a crap screwdriver - and then heat it until it glows red.
Small washers will get hot enough over a lighter, big, heavy washers may need a gas ring (if the Missus lets you!!)
Then drop it into cold water to anneal it.
One washer fit for reuse.